Establishing a voice call

ABSTRACT

A user equipment (UE), which is able to use a plurality of different wireless access technologies, receives a request to establish a voice call. In response to the request, the UE determines whether voice over a first wireless access technology of the different wireless access technologies is supported, and responsive to determining that voice over the first wireless access technology is not supported, the UE attempts to establish the voice call over a second wireless access technology of the different wireless access technologies.

BACKGROUND

Mobile communications networks allow user equipments (UEs) to establishwireless communications with other endpoints. A mobile communicationnetwork can include wireless access network nodes that providerespective coverage areas (also referred to as “cells”). A UE that iswithin a particular coverage area is able to establish a connection withthe corresponding wireless access network node.

BRIEF DESCRIPTION OF THE DRAWINGS

Some implementations are described with respect to the followingfigures.

FIG. 1 is a block diagram of an example mobile communications network,according to some implementations.

FIG. 2 is a flow diagram of an example process performed by a userequipment (UE), according to some implementations.

FIG. 3 is a block diagram of an example UE, according to someimplementations.

DETAILED DESCRIPTION

Different wireless access technologies can be employed by mobilecommunications networks. With certain wireless access technologies,voice calls are performed in a circuit-switched (CS) domain. A “voicecall” can refer to a communications session in which at least one userspeaks to another party, which can be another user or a machine (e.g.voice answering systems). Performing communications in the CS domain caninvolve establishing circuits (also referred to as dedicated channels)in the mobile communications network for the duration of a communicationbetween endpoints.

An example of a wireless access technology that performs voice calls inthe CS domain is the Global System for Mobile Communications (GSM)wireless access technology. Some GSM networks provide Enhanced DataRates for GSM Evolution (EDGE) to support packet-switched (PS)communications of data. PS communications refer to communications inwhich data (e.g. emails, web browsing traffic, document transfertraffic, etc.) to be transmitted is divided into packets that can beindividually routed through a communications network. A packet caninclude a header and payload, where the payload contains the actual datato be communicated, and the header includes information that is used bycommunication devices in the network to direct each packet to a targetdestination.

Although a GSM/EDGE network can support communication of data in the PSdomain, voice communications are still communicated by the GSM/EDGEnetwork in the CS domain.

Another example of a wireless access technology that performs voicecommunications in the CS domain is the Wideband Code Division MultipleAccess (WDCMA) access technology.

Although reference is made to various example wireless accesstechnologies that perform voice communications in the CS domain, it isnoted that in other examples, other wireless access technologies alsoperform voice calls in the CS domain. Such wireless access technologiesare referred to as “legacy” wireless access technologies in the ensuingdiscussion.

A more advanced type of wireless access technology is provided by theLong-Term Evolution (LTE) standards, which are implemented by the ThirdGeneration Partnership Project (3GPP). The LTE standards are alsoreferred to as the Evolved Universal Terrestrial Radio Access (E-UTRA)standards. The LTE wireless access technology is a fourth generation(4G) wireless access technology that is capable of supporting voicecalls in the PS domain (referred to as voice-over-LTE or VoLTE).However, even though LTE is capable of supporting VoLTE, theconfiguration of a UE and/or of wireless access network nodes in an LTEnetwork may specify that the VoLTE is not supported. The UE and wirelessaccess network can communicate this VoLTE capability during initialaccess of the UE.

Although reference is made to LTE in the ensuing discussion, it is notedthat techniques or mechanisms according to some implementations can beapplied to other wireless access technologies, including other 4Gwireless access technologies, or fifth generation (5G) or later wirelessaccess technologies that support voice communications in the PS domain.

A UE may be capable of using multiple different wireless accesstechnologies, including, as examples, the LTE wireless access technologyand a legacy wireless access technology such as WCDMA or GSM/EDGE (orany other wireless access technology that performs voice calls in the CSdomain). In examples where the UE is able to use both the LTE wirelessaccess technology and a legacy wireless access technology, the UE mayrespond to a request for a voice call by attempting to establish a VoLTEcall. An example of a request to establish a voice call is a request toestablish an emergency voice call, such as by dialing 911 or othersimilar numbers designated for emergency calls. When a user requests anemergency call, the user expects that the emergency call will beestablished relatively quickly.

However, where the UE uses multiple different wireless accesstechnologies including the LTE wireless access technology and a legacywireless access technology, there are two scenarios associated with theUE's attempt to establish the emergency voice call. In a first scenario(scenario 1), wireless coverage (with the UE's home network or a visitednetwork, where a visited network is a network of an operator with whichthe home network operator of the user has an existing roaming agreement)is available and the UE can scan and detect multiple wireless accesstechnologies including LTE. Since LTE wireless access is available andUE is able to use LTE, UE starts initial access (by performing attach)to the LTE bands. Once a voice call is initiated, UE initiates standardprocedures to either establish a voice call over LTE (if VoLTE isconfigured and supported by the UE) or initiates a circuit-switched (CS)fallback (CSFB) procedure so that the network can redirect the UE tolegacy wireless access networks and attempt the emergency call in the CSdomain.

In a second scenario (scenario 2), if UE is out of wireless coverage (inother words, the UE is out of wireless coverage with the UE's homenetwork or a visited network), the UE will first attempt establishing anemergency access to an LTE wireless access network (as the UE uses LTE).This initial attempt may or may not be successful. In both scenarios (1and 2), there is a delay in call setup because UE is attempting LTEaccess while VoLTe is not supported. With scenario 2, the delay can beavoided or reduced using techniques or mechanisms according to someimplementations of the present disclosure. In such scenario 2, the UEdetects LTE coverage and attempts to attach to the LTE network inresponse to the request for an emergency voice call. In some cases, thenetwork may accept the attach request from the UE, and may cause a CSfallback procedure to be performed to route the emergency voice call inthe CS domain (e.g. in a WCDMA or GSM network) rather than in the PSdomain of the LTE network. The emergency voice call can then be set upaccordingly in the CS domain of the GSM network. Such a process thatinvolves CS fallback can take from four to six seconds (for example) tocomplete the establishment of the emergency voice call.

In cases where the LTE network rejects the LTE attach attempt by the UE(such as by the LTE network sending a rejection with cause 15 toindicate “no suitable cells in the tracking area”), then the UE canattempt to initiate the emergency voice call in all other trackingarea(s) in all LTE frequency bands (bands in other frequency ranges)used by the UE. Such a scan of other LTE bands can take a relativelylong time, sometimes as long as or longer than 20 seconds, depending onthe number of LTE bands to be scanned by the UE. After completing thescan of the other LTE bands and determining that no suitable cells inLTE bands are available, the UE then switches to the legacy wirelessaccess technology to establish the emergency call in the CS domain. Thesetup time for the emergency voice call in this latter scenario (wherethe LTE network rejects the LTE attach attempt by the UE) can take up toor more than 20 seconds.

In either the CS fallback case or the case where the LTE attach attemptof by the UE is rejected, the time taken to establish the emergencyvoice call may be deemed excessively long and unacceptable consideringthe nature of the emergency calls.

Although the foregoing refers to issues associated with establishing anemergency voice call, it is noted that techniques or mechanismsaccording to some implementations can also be applied to other types ofvoice calls.

In accordance with some implementations of the present disclosure, a UEis able to more quickly establish a voice call (e.g. an emergency voicecall or a non-emergency voice call) in a context where the UE is able touse multiple wireless access technologies, including a first wirelessaccess technology that supports voice calls in the PS domain and asecond wireless access technology that performs voice calls in the CSdomain.

FIG. 1 is a flow diagram of an example process performed by a UEaccording to some implementations. The UE receives (at 102) a request toestablish a voice call, such as an emergency voice call or anon-emergency voice call. The request is received in response to a userdialing a phone number, such as an emergency number or other number, onan input interface (e.g., keypad, touchscreen, etc.) of the UE. Inresponse to the request, the UE determines (at 104) whether voice over afirst wireless access technology (e.g., LTE wireless access technology)is supported. Responsive to determining that voice over the firstwireless access technology is not supported, the UE attempts toestablish (at 106) the voice call over a second wireless accesstechnology (e.g., a WCDMA, GSM/EDGE, or other legacy wireless accesstechnology that performs voice calls in the CS domain). Attempting toestablish the voice call over a wireless access technology refers toinitiating, by the UE, a procedure to attach to a wireless accessnetwork according to the wireless access technology. The attempt toestablish the voice call may or may not be successful. Attempting toestablish a voice call over a wireless access technology can also bereferred to as “initiating establishment of a voice call over a wirelessaccess technology.”

In response to determining that voice over the first wireless accesstechnology is supported, the UE attempts to establish (or initiatesestablishment of) (at 108) the voice call over the first wireless accesstechnology, to perform the voice call in the PS domain.

With the process according to FIG. 1, the initial access (and proceduresfollowing initial access) of the first wireless access technology can bebypassed when the UE determines that voice over the first wirelessaccess technology is not supported, to allow for potentially quickerestablishment of the voice call over the second wireless accesstechnology.

FIG. 2 is a block diagram of an example mobile communications networkthat includes network nodes that operate according to a first wirelessaccess technology (e.g. LTE wireless access technology) and networknodes that operate according to a second wireless access technology(e.g. legacy wireless access technology).

FIG. 2 shows a coverage area 202 of an LTE wireless access network node204, and a coverage area 206 of a legacy base station 208. A wirelessaccess network node or base station refers to a node that is able towirelessly communicate over wireless links with UEs. Although just oneLTE wireless access network node 204 and one legacy base station 208 aredepicted in FIG. 2, it is noted that in other examples, there can bemultiple LTE wireless access network nodes 204 that provide respectivecoverage areas 202, and multiple legacy base stations 208 that providerespective coverage areas 206.

In an LTE network, a wireless access network node can be implemented asan enhanced Node B (eNB). Although reference is made to eNBs in theensuing discussion, it is noted that techniques or mechanisms accordingto the present disclosure can be applied with other types of wirelessaccess network nodes that operate according to other protocols.

The eNB 204 is connected to an LTE core network 210, which includesvarious core network nodes. As examples, the core network nodes caninclude a serving gateway (SGW) and a packet data network gateway(PDN-GW). The PDN-GW is the entry and egress point for data communicatedbetween a UE in the LTE network and a packet data network (PDN) 212,e.g. the Internet or another network. The SGW routes and forwardstraffic data packets of a UE between the eNB 204 and PDN-GW. The SGW canalso act as a mobility anchor for the user plane during handoverprocedures. The LTE core network nodes can also include a control nodereferred to as a mobility management entity (MME), which performsvarious control tasks associated with the LTE network. For example, theMME can perform idle mode mobile device tracking and paging, beareractivation and deactivation, selection of a serving gateway when amobile device initially attaches to the E-UTRA network, handover of theUE between eNBs, authentication of a user, generation and allocation ofa temporary identity to a mobile device, and so forth. In otherexamples, the MME 116 can perform other or alternative tasks.

The legacy base station 208 is connected to a legacy core network 214,which can include various legacy core network nodes. If the legacy corenetwork 214 is a GSM core network, then examples of the core networknodes include a serving GPRS (General Packet Radio Service) support node(SGSN) that is responsible for delivery of data packets from and to theUEs, and a gateway GPRS support node (GGSN) that is responsible forinternet working to an external packet data network, such as the PDN212. The legacy core network 214 can also include a mobile switchingcenter (MSC) to provide CS communications, such as CS voice calls.

Other core network nodes can be provided with other types of legacy corenetworks.

In the example of FIG. 2, a UE 220 is located within the coverage areas202 and 206 of the eNB 204 and the legacy base station 208,respectively. Thus, if the UE 220 is able to use both the LTE wirelessaccess technology and a legacy wireless access technology, the UE 220 isable to establish connections with either the eNB 204 or the basestation 208. In accordance with some implementations, the UE 220 is ableto perform tasks according to FIG. 1 to allow for quicker establishmentof a voice call.

FIG. 3 is a block diagram of an example UE 220, according to someimplementations. The UE 220 includes a processor (or multipleprocessors) 302, and multiple wireless interfaces 304 and 306. Aprocessor can include a microprocessor, a microcontroller, a hardwareprocessor module or subsystem, a programmable integrated circuit, aprogrammable gate array, or processing hardware.

The wireless interface 304 can perform wireless communications with amobile communications network according to a first wireless accesstechnology (e.g. LTE wireless access technology), and the secondwireless interface 306 is able to perform wireless communicationsaccording to a second wireless access technology (e.g., a legacywireless access technology). Although two separate wireless interfaces304 and 306 are shown in FIG. 3, it is noted that in other examples, awireless interface is able to communicate using different wirelessaccess technologies. Note that the UE may be able to attach to awireless access technology one at a time, or alternatively, the UE mayattach to multiple wireless access technologies concurrently.

The UE 220 also includes a storage medium (or storage media) 308, whichcan store a collection 310 of device configuration parameters and voicecall establishment instructions 312. Although FIG. 3 shows thecollection 310 of device configuration parameters and the voice callestablishment instructions 312 being part of the same storage medium308, it is noted that in other implementations the collection 310 ofdevice configuration parameters and the voice call establishmentinstructions 312 can be stored in separate storage media.

The collection 310 of device configuration parameters can includevarious parameters that relate to a configuration of the UE 220. One ofthe device configuration parameters of the collection 310 can be a VoLTEparameter 314 to indicate whether or not VoLTE is supported. Moregenerally, the parameter 314 can indicate whether or not a voice call ina PS domain is supported. If the VoLTE parameter 314 is set to a firstvalue, then that indicates that VoLTE is supported; however, if theVoLTE parameter 314 is set to a second value, then that indicates thatVoLTE is not supported.

Examples of other device configuration parameters in the collection 310can include a parameter to indicate that the UE 220 is LTE capable, aparameter (or parameters) to identify the LTE bands supported, aparameter indicating whether or not LTE is preferred, and so forth.

The collection 310 of device configuration parameters may be staticallyconfigured in the UE 220 (such that the device configuration parameterscannot be changed during operation of the UE 220). In other examples,the collection 310 of device configuration parameters can be dynamicallyset by a mobile communications network during operation of the UE 220 inthe mobile communications network. For example, the mobilecommunications network can send a message to the UE 220 to set one ormore of the device configuration parameters, including the VoLTEparameter 314.

The collection 310 of device configuration parameters can be stored in aSubscriber Identity Module (SIM) card of the UE 220, or can be stored inanother storage medium of the UE 220.

The voice call establishment instructions 312 include machine-readableinstructions that are executable by the processor(s) 302. The voice callestablishment instructions 312 when executed by the processor(s) 302 canperform tasks according to some implementations of the presentdisclosure, including the tasks of FIG. 1, for example. More generally,the voice call establishment instructions 312 are able to firstdetermine whether or not voice over a first wireless access technology(e.g., VoLTE) is supported, and based on this determination, can performestablishment of a requested voice call over either the first wirelessaccess technology (e.g. LTE wireless access technology) or a secondwireless access technology that supports just voice calls in a CSdomain.

The voice call establishment instruction 312 can determine whether ornot voice over the first wireless access technology is supported basedon accessing the VoLTE parameter 314.

By employing techniques or mechanisms according to some implementations,quicker voice establishment can be accomplished in a UE that usesmultiple different types of wireless access technologies.

The storage medium (or storage media) 308 can include non-transitorycomputer-readable or machine-readable storage medium (or storage media),which can include one or multiple different forms of memory includingsemiconductor memory devices such as dynamic or static random accessmemories (DRAMs or SRAMs), erasable and programmable read-only memories(EPROMs), electrically erasable and programmable read-only memories(EEPROMs) and flash memories; magnetic disks such as fixed, floppy andremovable disks; other magnetic media including tape; optical media suchas compact disks (CDs) or digital video disks (DVDs); or other types ofstorage devices. Note that the instructions discussed above can beprovided on one computer-readable or machine-readable storage medium, oralternatively, can be provided on multiple computer-readable ormachine-readable storage media distributed in a large system havingpossibly plural nodes. Such computer-readable or machine-readablestorage medium or media is (are) considered to be part of an article (orarticle of manufacture). An article or article of manufacture can referto any manufactured single component or multiple components. The storagemedium or media can be located either in the machine running themachine-readable instructions, or located at a remote site from whichmachine-readable instructions can be downloaded over a network forexecution.

In the foregoing description, numerous details are set forth to providean understanding of the subject disclosed herein. However,implementations may be practiced without some of these details. Otherimplementations may include modifications and variations from thedetails discussed above. It is intended that the appended claims coversuch modifications and variations.

1. A method comprising: receiving, by a user equipment (UE) that is able to use a plurality of different wireless access technologies, a request to establish a voice call; and in response to the request: determining, by the UE based on accessing a device configuration parameter stored in the UE, whether voice over a first wireless access technology of the different wireless access technologies is supported, wherein the UE determines that voice over the first wireless access technology is supported responsive to detecting that the device configuration parameter is set to a first value, and the UE determines that voice over the first wireless access technology is not supported responsive to detecting that the device configuration parameter is set to a second, different value, the device configuration parameter being part of a collection of configuration parameters stored in the UE that relate to a configuration of the UE, and responsive to determining that voice over the first wireless access technology is not supported, attempting to establish, by the UE, the voice call over a second wireless access technology of the different wireless access technologies.
 2. The method of claim 1, wherein the first wireless access technology supports a voice call in a packet-switched domain.
 3. The method of claim 2, wherein the second wireless access technology performs a voice call in a circuit-switched domain.
 4. The method of claim 1, wherein the first wireless access technology is a Long-Term Evolution (LTE) wireless access technology.
 5. The method of claim 1, wherein receiving the request to establish the voice call comprises receiving a request to establish an emergency voice call.
 6. The method of claim 1, further comprising, in response to the request: responsive to determining that voice over the first wireless access technology is supported, attempting to establish, by the UE, the voice call over the first wireless access technology.
 7. The method of claim 1, wherein the device configuration parameter is stored in a Subscriber Identity Module (SIM) of the UE.
 8. (canceled)
 9. The method of claim 1, wherein the device configuration parameter is dynamically configured by a mobile communications network, the method further comprising changing a value of the device configuration parameter between the first and second values responsive to a message received from the mobile communications network.
 10. The method of claim 1, wherein the determining and the attempting to establish are performed in response to the UE being out of wireless coverage of a home network of the UE.
 11. A user equipment (UE) comprising: at least one wireless interface to communicate with a mobile communications network according to one or more of a plurality of different wireless access technologies; and at least one processor configured to: receive a request to establish a voice call; and in response to the request: determine, based on accessing a device configuration parameter stored in the UE, whether voice over a first wireless access technology of the different wireless access technologies is supported, wherein the at least one processor is configured to determine that voice over the first wireless access technology is supported responsive to detecting that the device configuration parameter is set to a first value, and determine that voice over the first wireless access technology is not supported responsive to detecting that the device configuration parameter is set to a second, different value, the device configuration parameter being part of a collection of configuration parameters stored in the UE that relate to a configuration of the UE, and responsive to determining that voice over the first wireless access technology is not supported, initiate establishing the voice call over a second wireless access technology of the different wireless access technologies.
 12. The UE of claim 11, wherein the determining of whether voice over the first wireless access technology is supported comprises determining whether voice over Long-Term Evolution (LTE) is supported.
 13. The UE of claim 11, wherein the initiating the establishing of the voice call over the second wireless access technology comprises initiating the establishing of the voice call in a circuit-switched domain.
 14. The UE of claim 11, wherein the at least one processor is configured to further, in response to the request: responsive to determining that voice over the first wireless access technology is supported, initiate establishing the voice call over the first wireless access technology.
 15. The UE of claim 14, wherein the initiating the establishing of the voice call over the first wireless access technology comprises initiating the establishing of the voice call in a packet-switched domain.
 16. The UE of claim 11, further comprising a storage medium to store the device configuration parameter.
 17. The method of claim 1, wherein the device configuration parameter if set to the first value indicates that voice over the first wireless access technology is supported, and the device configuration parameter if set to the second, different value indicates that voice over the first wireless access technology is not supported.
 18. An article comprising at least one non-transitory machine-readable storage medium storing instructions that upon execution cause a user equipment (UE) to: receive a request to establish a voice call, wherein the UE is able to use a first wireless access technology that supports voice communication in a packet-switched domain and a second wireless access technology that performs voice communications in a circuit-switched domain; and in response to the request: determine, based on accessing a device configuration parameter stored in the UE, whether voice over the first wireless access technology is supported, wherein the UE determines that voice over the first wireless access technology is supported responsive to detecting that the device configuration parameter is set to a first value, and the UE determines that voice over the first wireless access technology is not supported responsive to detecting that the device configuration parameter is set to a second, different value, the device configuration parameter being part of a collection of configuration parameters stored in the UE that relate to a configuration of the UE, responsive to determining that voice over the first wireless access technology is not supported, initiate establishing the voice call over the second wireless access technology, and responsive to determining that voice over the first wireless access technology is supported, initiate establishing the voice call over the first wireless access technology.
 19. The article of claim 18, wherein the request to establish the voice call is a request to establish an emergency voice call responsive to a user dialing an emergency number.
 20. The article of claim 18, wherein the voice call over the second wireless access technology is in the circuit-switched domain, and wherein the voice call over the first wireless access technology is in the packet-switched domain.
 21. The UE of claim 11, further comprising a Subscriber Identity Module (SIM) to store the device configuration parameter. 